Wayne and Beejunk: JACK with built-in MacBook soundcard

wayne wayne at jawnee.org
Mon Jul 6 13:05:17 BST 2009

On Sat, 2009-07-04 at 17:54 -0700, Paul DeShaw wrote:

> Hello,
> Have either of you been able to use JACK with the built-in sound on
> your 1st gen MacBooks?

    after lots of testing/playing, i was able to get it to work
reliably, though with weird crackling on some configs.  i have not used
it recently (i have an external FireWire Edirol Fa-66 interface that
works well with UBS 8.04 Hardy).  i took some notes on it actually, in
case people needed help in the future.  i worked from a blog that had
lots of good info:


the main trick was changing a "position_fix" parameter
in /etc/modprobe.d/local, though i did discover some weirdness depending
on the settings.  here is the summary of my different position_fix

JACK position_fix

      * position_fix=3 
              * ALSA/Pulse - crackly 
              * JACK - solid 
      * position_fix=2 
              * ALSA/Pulse - clear 
              * JACK - delay/XRUNs 
      * position_fix=1 
              * ALSA/Pulse - no crackle on headphones, speakers
                sometimes.  could be speakers or crackles may disappear
                running sirq script (i.e. updates real time priorities
                of important audio processes 
              * JACK - solid 
      * position_fix=0/commented out 
              * ALSA/Pulse - works/clear 
              * JACK - delays/XRUNS 

the 2 issues i was having were:

      * consistently on my MacBook, in UBS i often get some various
        crackling using the internal sound adapter, more noticeable in
        the speakers than headphones.  this could be a problem with the
        levels, but i could never quite get it cleared up.  when i was
        using Mac OS X, there were no crackles.  playing with the
        position_fix seemed to make more/less crackles as indicated
      * when JACK would work (depending on position_fix), the left
        channel would simply provide no output when in real time mode,
        either playback 1 or 3 (speakers 1/2, headphones 3/4 on my
        MacBook).  however, this problem kind of fixed itself in some
        update, which i believe was when i starting using a PPA provided
        by Khashayar at https://launchpad.net/~khashayar/+archive
> Sometimes I'd just like to do a little editing or whatnot away from
> home. I don't have a portable interface; it's built into a MIDI
> keyboard controller.  Not something I want to lug around.   But when I
> try using the built-in card, no matter how I tweak the settings in
> JACK, I get a ton of either xruns or hardware wakeup errors.  Do you
> know a way to fix this?  If not, can you recommend a portable
> interface that works well with the MacBook and Hardy?

    i use the internal interface for editing on the road, but i have an
Edirol FA-66 that i think is great.  when i had not seen the light, and
still using Mac OS X/Logic, it never gave me any problems.  with
GNU/Linux, i get even better latency than was possible with Mac OS
X/Logic, and the interface works well (only with FreeBob... i have not
gotten FFDAO to work yet, but that may because i am using such an
outdated system) still.  the only problem is that the FireWire bus seems
to get messed up after long recording sessions, or long pauses with JACK
running but doing nothing.  this could be because i record to an
external FireWire drive on the same bus, which from my Mac days was
better (latency-wise) than recording to the system disk.  so, sometimes
i need to unplug everything from the FireWire bus.  Edirol was always
good with support, and i use it and the GNU/Linux MacBook at gigs for
live effects.  all no problems.

    hope this helps.  i have learned the hard way that it seems Apple
products are best at running Apple software.  though a long-time
GNU/Linux user, i got a Mac to do music (at the time FLOSS music
production was not where it is now), but quickly found it was just too
much of a compromise of my principles.  since, i have been making music
with FLOSS software on the MacBook, but it has been painful at times.
next time, plan on going with a laptop that supports FLOSS software/open
specs/etc., like system76 or Los Alamos computers.

peace, w

> Thanks,
> Paul D.
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